A heating system with flues cooperating in pairs, air supply stages located high and low, as well as a flue gas return at the level of the flue base, has been known from European Patent Application No. 0,183,908. In these only two air supply stages over the height of the flue, the supply of air and gas at the base of each flue forms the first stage, and the supply via hollow communicating channels and discharge slots, located at the same height for both adjacent flues, forms the second stage. Heating with only two air supply stages is not sufficient for optimal combustion and for minimizing the NO.sub.x formation in coke ovens with a chamber height exceeding, e.g., 4 m.